The invention relates to a rotor for an electric rotating machine, in particular a synchronous machine, comprising a shaft and at least one pole shoe, wherein the shaft has a first contact surface and wherein the at least one pole shoe has a second contact surface.
The invention also relates to an electric rotating machine, in particular a synchronous machine, comprising a rotor of said type.
The invention further relates to a method for producing a rotor of said type for an electric rotating machine, in particular a synchronous machine.
A rotor of said type finds application in particular in direct-starting synchronous salient-pole machines with mounted pole shoes. Mounted pole shoes are employed principally in large drives having a power rating of at least 1 megawatt. A separation joint is formed between the pole shoe and the shaft on which the pole shoe is mounted. An asynchronous starting of the synchronous salient-pole machine causes eddy currents to be induced in the mounted pole shoes, the surface of the pole shoes in particular being intensely heated by the eddy currents. In the course of being heated through, the pole shoes expand. The transverse force resulting therefrom in the separation joint is restrained primarily in a friction-locking manner. If the static friction is overcome, a heat-induced relative displacement occurs in the separation joint between pole shoe and shaft. In most cases a relative displacement of said kind happens abruptly and arbitrarily. The mass displacements associated therewith have a negative impact on the equilibrium state of the rotor and consequently on the oscillation behavior.
The pole shoes are preferably connected to the shaft by means of bolts. The static friction in the separation joint between pole shoe and shaft is therefore determined by the pretensioning forces and the coefficients of friction. In particular the coefficients of friction can be influenced by selective changes to the material properties and surface characteristics of the partners in the frictional engagement.
An electrical rotating machine having a salient-pole rotor composed of pole bodies and pole shoes is known from the patent specification U.S. Pat. No. 9,077,223 B2. The pole bodies are integrally formed in a single piece from a shaft, Each pole shoe is fixedly joined to the associated pole body by means of a plurality of bolts. When a pole shoe is fastened to the corresponding pole body with the aid of the bolts, a cone-shaped compression region is produced in the vicinity of the compression surface.
Each pole shoe or its corresponding pole body has at least one projection or recess in order to delimit the cone-shaped compression region in the vicinity of the compression surface.
An electric machine having a pole wheel comprising a plurality of poles is known from laid-open publication DE 44 15 224 A1, there being provided for each pole in said electric machine a pole body connected in a single piece to a yoke and having a field excitation winding surrounding the same and a pole shoe arrangement fastened to the end of the pole body by means of bolts. The intended aim with this construction is to provide a more effective means of intercepting the centrifugal forces occurring during the rotation of the pole wheel and acting on the pole shoe arrangement and the field excitation winding. For this purpose, the pole shoe arrangement comprises a retaining plate bolted onto the pole body and a pole shoe bolted solely to the retaining plate. The centrifugal forces occurring due to the field excitation winding are therefore intercepted by the retaining plate.
The laid-open publication US 2014/0333174 A1 describes an electric rotating machine comprising a salient-pole rotor that is composed of pole bodies. The pole bodies are integrally formed in a single piece from a shaft. The pole shoes form pole heads. Each pole shoe is fixedly connected to the associated pole body by means of a plurality of bolts. Each pole shoe or its corresponding pole body has at least one projection or recess in order to delimit a cone-shaped compression region in a compression zone. A cone-shaped compression region in a compression zone occurs when the pole shoe is connected to the corresponding pole body by means of the bolts.
The laid-open publication U.S. Pat. No. 3,089,049 A describes a salient-pole rotor comprising pole bodies and pole shoes, the pole bodies being releasably connected to the pole shoes by way of an integral construction.
The laid-open publication EP 2 876 783 A1 describes a salient-pole rotor comprising at least two radially outward facing pole bodies, each having a respective pole shoe, the pole shoe being wider in the circumferential direction than the respective pole body. The respective pole shoe has a radially inward facing, tapering projection, the respective pole body having, on its radial outer surface, a radially inwardly tapering groove complementary to the respective projection, the respective pole shoe and the respective pole body being connected in a mechanically releasable manner.
The object underlying the invention is to disclose a rotor for an electric rotating machine which, in comparison with the prior art, possesses a higher level of reliability and at the same time is easy and cost-effective to produce.